Blowing Wool - Supafil 40


Masonry cavity walls


Blowing Wool


Supafil 40 cavity wall insulation is a silicone treated non-combustible Glass Mineral Wool for injection into masonry cavity walls by approved Knauf Insulation contractors. The unique characteristics of Supafil 40 enable thermal compliance at a lower density compared to traditional loose glasswool.


  • Euroclass A1 non-combustible
  • British Board of Agrément approved
  • Suitable for new-build or retrofit
  • Installed by approved contractors - quick and clean to install
  • Injected after wall constructed, allowing empty cavity to be checked before installation



Thermal Conductivity (W/mK)Euroclass Reaction to Fire ClassificationPack DimensionsPack Weight (kg)Packs Per Pallet


Supafil 40 BBA logo - Certificate No: 88/2033
Eurofins Gold
A1 Euroclass Fire Rating
Green Guide Rating A+
CE Marking
Bureau Veritas

Declaration of Performance

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Additional Product Information


We care for the people who make our products, the people who use them and the world we all depend on.

 Whilst we are dedicated to supplying sustainable high performance insulation solutions for enhanced energy efficiency in buildings, we also continually strive for improvements in our manufacturing and supply chain operations so to improve quality and minimise our impact on the environment. All Knauf Insulation production locations have state-of-the-art manufacturing equipment and meet the highest quality standards as well as they are supported by an ongoing research and development program. All of our products including Supafil 40 are sustainably manufactured.

At Knauf Insulation, we have 7 key sustainability considerations:

  • to conserve natural resources
  • to reduce the evironmental effects of our own processes
  • Treating people fairly, along the supply chain
  • Delivering our products efficiently
  • Building a comfortable and healthy indoor environment
  • Performance reporting
  • Recognition